Electrochromic materials include those materials that change color in a persistent but reversible manner via an electrochemical reaction, i.e., generally having at least one colored state and at least one bleached or substantially colorless state.
Electrochromic devices, such as electrochromic eyeglasses, windows or shutter-type devices are well known in the art. Typically such devices are constructed such that the electrochromic material is sandwiched between two optically transparent substrates, e.g., glass or polymeric substrates. The surfaces of the substrate material in contact with the electrochromic material typically are provided with a layer of conductive material, such as indium tin oxide, which is in electrical communication with a voltage source. When the voltage is applied, current flowing through the electrochromic material induces an electrochemical reaction which results in coloration which reverses back to the initial clear or bleached state upon cessation of the voltage application.